MINERAL WOOL PRODUCT, METHOD FOR PRODUCING IT, AND GLUE FOAM THEREFOR

Abstract: Laminated mineral wool products which have to comply with high fire protection standards, such as building material belonging to Class A2 according to DIN 4102, require special production expenses if the laminating foil is to be reliably fastened with organic glue without downgrading its fire protection classification. By foaming the glue it is possible to manage with a fraction of the hitherto required quantity of glue without having to accept an essential lowering of glue performance. As a result, organic glue can be used without its fire load having to be neutralised by polluting flame-inhibiting agents. Furthermore the glue foam causes less problems during processing in production, reduces the charged quantity of glue, and reduces the required drying capacities. It is particularly suited for difficult applications such as laminating felt which is rolled for packaging or laminated panels comprising erect fibers.

Description: Description Mineral Wool Product. Method for Producing It. and Glue Foam Therefor The invention concerns a mineral wool product lami¬ nated with a foil by means of a glue, a method for pro¬ ducing such a mineral wool product, as well as the glue foam usable therefor. Mineral wool products laminated with a metal foil are e.g. known from DE-PS 24 60 508. In order to fasten the laminating sheet having the form of a metal foil on the mineral wool product, an inorganic glue is used. In this manner, an increase of the fire load of the laminated product due to the glue is avoided, and thus (despite the use of organic substances, however in small amounts, as binders) classification e.g. into material class A2 - fireproof construction materials - as specified by DIN 4102 is achieved without difficulties. However, in the case of using an organic glue for fastening the laminat¬ ing sheet at otherwise unmodified formation of the min¬ eral wool product, as a rule merely conformity with mate¬ rial class Bl - hardly inflamable construction materials - as specified by DIN 4102 is achieved as in fire behav¬ ior testing, the organic glue accelerates the progress of the decomposition front so intensely that the require¬ ments to a fireproof classification generally cannot be satisfied any more. It was, however, found that the available inorganic glues on the basis of water glass or silica sol for the purpose of fastening the lamination on mineral wool prod¬ ucts are not fully satisfactory in many cases. This is particularly true for mineral wool products having low flexural strength as these inorganic glues are relatively brittle and have a tendency to delaminate when the prod- uct is bent. Particularly one main applicational field for such laminated mineral wool products, rolled felt, requires a glue having good bending flexibility, for oth¬ erwise the adhesive bond will be impaired already while the felt web is rolled. Inorganic glues therefore could not gain acceptance for many practical applications, such as in particular for laminated rolled felt, and thermo- activated organic glues which have a better adhesive ca¬ pacity and which are more elastic were used instead. In order to obtain a fireproof classification of min¬ eral wool products while using organic glue, however, ad¬ ditional measures are required, above all the additional use of fireproofing agents. Using highly effective fire- proofing agents, such as antimony trioxide, is unaccept¬ able for reasons of protection of the environment, and less pollutant substitutes herefor, such as fireproofing agents which release water or nitrogen, are much less ef¬ fective. In order to nevertheless obtain a fireproof classification of the product, the amount of used organic glue must consequently be kept as small as possible, which in turn makes it difficult to obtain the perfect adhesive bond. Thus obtaining a fireproof classification for a mineral wool product having a lamination fastened by means of organic glue is the result of much experimen¬ tation for obtaining a useful compromise between the technical requirements of fire protection and those of bonding, and precise monitoring of current production as to keeping all the parameters within narrow limits is a prerequisite if the fireproof classification is not to be endangered. With respect hereto, the invention is based on the object of providing a mineral wool product of the type mentioned above which is laminated with a foil adhering well even under flectional stress and which - if at all - at the most requires fireproofing agents which are non- pollutant in order to reliably obtain classification into a more favorable fire protection classification for con¬ struction materials, such as material class A2 as speci¬ fied by DIN 4102. This object is attained in accordance with the inven¬ tion in that the glue represents a reticulate connecting structure between the fibers in the region of the product surface and the foil. The reticulate structure of the glue substance en¬ ables concentration of the glue in single glue accumula¬ tions with glue-free spots in between them. In this man- ner, a good and - when viewed macroscopically - suffi¬ ciently complete adhesive effect may be achieved between the fibers adjacent the surface of the mineral wool prod¬ uct and the foil, without, however, an actually complete, i.e. a practically full surface glue film being required. Such a continuous glue film is replaced by the network of lines and dots of the glue structure on and between the surfaces of the fibers and the foil to be connected, with a reduction in the glue quantity being much greater rela¬ tive to the decrease in the adhesive effect of the glue. In this manner, the amount of used glue may be reduced to such an extent that the reduced fire load of the product permits its fireproof classification. The reduction in the quantity of glue achieved in accordance with the in¬ vention brings about considerable additional advantages in practical terms e.g. also in view of glue costs and reduced capacities for drying or curing the glue. A mineral wool product in accordance with the inven¬ tion may be obtained by applying a layer of the glue onto one of the surfaces to be connected and subsequently joining together the surfaces to be connected if the glue is applied in the form of foam. This results in the desired reticulate connecting structure in a reliable and well controllable manner, as the pore sizes and the further properties of the foam are well controllable, and thus the reticulate structures may be determined which occur during the lamination process or while the foam degenerates on and between the fiber surfaces and the foil surface. Application of the glue as a foam layer at the same time guarantees uniform distri¬ bution of the glue within the volume element predeter¬ mined by the thickness of the glue layer adjacent the foil surface, whereby the small quantity of glue used may take optimum effect in locking among each other the fi¬ bers located close to the surface and fastening the foil thereto. If a metal foil is used as the foil, for which pur- pose particularly an aluminum foil is suited, a fire- proofing agent may, as a rule, be dispensed with entirely in view of the small quantity of glue used for fastening the foil without thereby endangering the fireproof clas¬ sification. If the foil, however, contains organic sub- stances, as is particularly the case with a frequently preferred aluminium/kraft paper compound foil, the or¬ ganic proportion thus increased may, if necessary, be neutralised in a simple manner by a non-pollutant fire- proofing agent, if the combined fire load from the small quantity of glue and the organic foil component should at all threaten to endanger a fireproof classification. Application of the glue is preferably carried out in such a manner that the layer of glue is spread onto one surface of the foil, and the side of the foil thus coated is then laid on and pressed against the fibrous surface. In comparison with another conceivable method, namely the glue at first being applied to the fibrous surface and the foil subsequently being laid on, this results in the advantage that spreading the glue on the foil is techni- cally easier and intimate bonding of the glue and the foil is ensured. Subsequent impression of the glue layer arranged on the foil surface into the fibrous surface nevertheless ensures intimate bonding of the glue and the fibers, as in the case of application in the form of foam, quite a considerable layer thickness is provided which can readily be penetrated by the fibers. Such a glue foam is obtainable through frothing by blowing agent which is known per se. Preferably, however, the glue foam according to the invention is produced me¬ chanically by the mechanical frothing method or by means of dissolver disks. In this case, a foam suited for spread application is formed by beating in air, which foam may be applied to the lamination, whereupon the lamination is laid onto the mineral wool. The glue mix¬ ture preferably contains a certain amount of water in or¬ der to reduce its viscosity to such an extent that me¬ chanical frothing by the mechanical frothing method by means of dissolver disks is facilitated. The glue mixture preferably used herefor is an aqueous mixture of organic glue, foaming agent, and foam stabilising agent, which may optionally contain an addition of fireproofing agent if required. On the other hand, the glue foam may also be produced in accordance with a chemical frothing method wherein the blowing gas is generated by chemical reaction. Particu¬ larly in this case, using a water-free organic glue is also conceivable, which in a given case might remain in the three-dimensional foam structure without any essen¬ tial degeneration of the foam occurring. As a glue for laminating with foil, numerous organic glues are known in the prior art. Within the scope of the invention, particularly good results were achieved with Mowilith®, a thermoplastic synthetic resin glue of Hoechst AG, and Vinnapas®, a thermoplastic synthetic resin glue of Wacker Chemie. The aqueous dispersion of the organic glue moreover contains a foaming agent which is known per se, such as a surfactant having a certain film forming capacity and thus supporting the generation of foam in liquids. The glue mixture furthermore contains a foam stabilising agent which is known per se, counteracting a premature decomposition of the foam. The foam is suited for spread application and has a consistency similar to that of whipped cream or beaten egg-whites, with the foam volume corresponding to approximately the five- or sixfold of the previous liquid volume. Frothing the glue used for lamination, preferably in a frothing device by means of dissolver disks, consider¬ ably increases not only the volume of the glue mixture; it also ensures that all the fibers in the vicinity of the mineral wool product surface are exposed to contact with the glue, whereby a three-dimensional reticulate connecting structure is created, i.e. a three-dimensional accumulation of glue which is line or dot shaped when viewed from above, between the fibrous surfaces to be connected and the foil surface, with zones free of glue or comprising little glue between the accumulations. The foam spread on the lamination penetrates into the layer adjacent the surface of the mineral wool product and en¬ closes the mineral fibers located there. If the glue contains free water, the foam bubbles subsequently start to burst during curing of the glue foam, with the glue thus released from areas in between the individual fivers getting into contact with the fi- bers due to adhesion. This establishes a particularly in¬ timate bond between the fibers and the glue, whereby the already intimate bond between the glue and the lamination foil takes effect such as to improve adhesion of the foil. The basic features of the reticulate foam structure are preserved here, and on condition of a corresponding foam consistency its three-dimensional character is pre¬ served, too, even though the number of connections bridg¬ ing larger gaps between fiber surfaces and foil surface, where located at a distance from each other, tends to de- crease. The amount of applied organic glue conventionally is approximately 30 g/m 2 (dry) for usual applications, such as for example lamination of rolled felt. According to the invention, this amount may considerably be reduced without excessively deteriorating the adhesive capacity. Thus the amount of glue foam spread on the foil in accor¬ dance with the invention is in the range between 2 and 20 g/m 2 (dry), with this upper limit being reserved for very tricky applications, such as laminating the front surface of a fiber product having the preferred fiber orientation essentially perpendicular thereto. Such a task occurs, for instance, in laminating so-called lamellar panels, i.e. panels having a particularly high compression resis- tance where the preferred fiber orientation is essen¬ tially perpendical to the two major surfaces. In such cases, the glue penetrates particularly easily and deeply into the surface of the mineral wool product and thus a relatively large quantity of glue is necessary in order to ensure the desired perfect bonding of the region adja¬ cent the surface. In accordance with the invention, a quantity of glue in the range between 4 and 15 g/m 2 (dry), in particular between 5 and 10 g/m 2 (dry) is generally sufficient. For usual applications such as for lamination of rolled felt, applied amounts in the range of 5 g/m 2 or less are more typical for the present invention. According to an embodiment of the glue foam used in accordance with the invention, it contains: 25-40%(wt. ) dispersion of an organic glue (water content 60%, corresponding to 10 to 16%(wt.) dry glue sub¬ stance) 0.5-1.5%(wt. ) foaming agent 0.05-0.3%(wt. ) foam stabilising agent. fireproofing agent (flame-inhibit¬ ing agent) in the amount required for a specific application balance water. Suited mineral wool products are e.g. mineral wool panels, mineral wool felts and mineral wool nonwovens. A particularly preferred field of application of the pre- sent invention is lamination of rolled felt, because in view of the rolling process it presents the highest re¬ quirements which are particularly well satisfied by the invention. Example 1 33%(wt.) Mowilith® Dispersion DM132 (water content 60%), a thermoplastic syn¬ thetic resin glue of Hoechst AG, l%(wt. ) foaming agent W53 of Zschimmer & Schwarz 0.1%(wt.) foam stabilising agent PS1 of Zschimmer & Schwarz balance water This mixture was frothed in an agitator and applied onto an aluminum foil in an amount of 5 g/m 2 Mowilith® (dry) by means of a doctor blade. Afterwards a rollable mineral wool felt was laid on the foam-coated aluminum foil and bonded in temperature. Here it was found that the foil presented an excellent adhesion to the mineral wool product although the used quantity of glue was greatly reduced in comparison with hitherto customary amounts of glue. Example 2 32.7%(wt.) Vinnapas® Dispersion EP 177 (water content 60%) of Wacker Chemie (a vinyl acetate and ethylene copoly- mer) 0.64%(wt. ) W53 foaming agent of Zschimmer & Schwarz 0.19%(wt. ) PS1 foam stabilising agent of Zschimmer & Schwarz 1.6%(wt. ) Luvogard (phosphoric acid ester) as a fireproofing agent 12.8%(wt.) BACO SF4 (aluminum hydroxide) as a fireproofing agent balance water This mixture was frothed by means of dissolver disks in accordance with the mechanical frothing method and ap¬ plied onto an aluminum/kraft paper compound foil by means of a doctor blade. Subsequently, a rollable mineral wool felt was laid on the foam-coated compound foil and bonded while heated. Here, as well, the result was an excellent adhesion of the compound foil to the mineral wool felt at an amount of organic glue reduced by more than 80% in comparison with hitherto customary amounts of glue. As the fireproofing agent, a combination of phospho¬ ric acid ester and aluminum hydroxide is used. Phosphoric acid ester is considerably more cost-intense than alumi¬ num hydroxide, however it also serves as a softener for the glue. Thus, where it is required to reduce brittle- ness and improve elasticity of the glue, the phosphoric acid ester content in the fireproofing agent may be in¬ creased; for the rest it is kept low in order to minimise costs.

Claims: Claims 1. Mineral wool product laminated with a foil by means of a glue, characterised in that said glue represents a reticulate connecting structure between the fibers in the area of product surface and foil. 2. Mineral wool product laminated with a foil by means of a glue layer, obtainable by applying a layer of said glue on one of the surfaces to be combined and subsequently joining together said surfaces to be combined, characterised in that said glue is applied in the form of foam. 3. Mineral wool product according to claim 1 or 2, cha¬ racterised in that said foil is a metal foil, in par¬ ticular an aluminum foil. 4. Mineral wool product according to claim 1 or 2, cha¬ racterised in that said foil contains organic sub¬ stances, in particular it is an aluminum/kraft paper compound foil. 5. Method for producing a mineral wool product according to any one of claims 1 to 4, characterised in that said glue is applied as a layer of foam onto the pro¬ duct surface, and subsequently said foil is applied to said mineral wool product, and said glue is cured in temperature. 6. Method according to claim 5, characterised in that said glue foam is produced by means of a mechanical method shortly before its use from a mixture contai- ning an organic glue, a foaming agent, a foam stabi- user, in a given case a fireproofing agent (flame- inhibiting agent), and water. Method according to any one of claims 4 or 5, charac¬ terised in that said glue foam is applied in an amount of 2 to 20 g/m 2 , preferably 4 to 15 g/m 2 , and in a particularly preferred manner 5 to 10 g/m 2 , all these figures on the basis of the weight of the dried glue substance. Glue foam for use in the method according to any one of claims 5 to 7, characterised by a mixture of 10 - 16% by weight organic glue (dry) 0.5 - 1.5% by weight foaming agent 0.05 - 0.3% by weight foam stabiliser fireproofing agent as re- quired balance water, which is foamed in accordance with a mechanical me¬ thod. 9. Glue foam according to claim 8, characterised by in- troduction of said organic glue in the form of Mowi¬ lith ® Dispersion DM132 (water content: 60%) of Hoechst AG. 10. Glue foam according to claim 8, characterised by in- troduction of said organic glue in the form of Vin- napas ® EP 177 (water content: 60%) of Wacker Chemie.

Inventors: KUMMERMEHR HANS, KUMMERMEHR, HANS
Applicants: KUMMERMEHR HANS, SAINT GOBAIN ISOVER, ISOVER SAINT-GOBAIN, KUMMERMEHR, HANS
Application year: 1994
Main classification: B32B7
IPC codes: A01G31, B32B5, B32B7, B32B15, B32B19, E04B1